From bulky to bony -- Jake Gyllenhaal tells Us Weekly his gaunt appearance and dramatic weight loss transformation is all for the sake of art.

The 32-year-old heartthrob attended the 17th Annual Hollywood Film Awards on Monday, Oct. 21 looking dramatically different with his hair grown out and a significantly slimmer physique, his sharp cheekbones protruding noticeably. On the red carpet, he told Us his new look is entirely for his character in the upcoming thriller, Nightcrawler, currently shooting in Los Angeles.

In it, Gyllenhaal plays a struggling, freelance crime reporter named Lou who stumbles upon the decrepit underground world of Los Angeles. "It takes place," the actor said, "in a land where I think there is a desert in a lot of ways, great opulence, and at the same time, great vastness and emptiness."

Gyllenhaal explains, "I knew that [Lou] was literally and figuratively hungry," adding that he's emulating his character by getting into a "mode where I was always a bit hungry."

The nearly skeletal method actor is following in the footsteps of fellow Hollywood hunks: Matthew McConaughey dropped 50 pounds in his role as an HIV-positive man in the critically-acclaimed movie Dallas Buyers Club. Christian Bale also lost an astounding 65 pounds in 2004 for his role as an insomniac in The Machinist.

Gyllenhaal's latest physical transformation is not his first: In 2010, the Oscar nominee added major muscle to his physique to prep for his role in Disney's Prince of Persia. The actor revealed then that he would eat six small meals loaded with protein, carbs and fats. Gyllenhaal, however, says there was no special diet to keep his weight down for Nightcrawler. "I just love this movie," he says. "That’s how I did it. There really was no technique."

Nightcrawler co-stars Bill Paxton and Rene Russo. Gyllenhaal, meanwhile, is co-producing the film with Tony Gilroy, who's directing, too. "We're shooting on a 24-hour schedule and we have like no money," Jake told Us at the Toronto International Film Festival in September. "But it's a really solid screenplay."

The actor accepted the Hollywood Supporting Actor Award at Monday night's event from his Prisoners co-star Viola Davis. He shared on stage, "I accept this award for all the light that comes when you stop fearing the dark. Thank you so much."